Cooling baffle and tamper shield for underground transformer vaults



July 30, 1968 c R AcKER 3,394,645

COOLING BAFFL A'ND TAMPER SHIELD FOR UNDERGROUND TRANsFoRNER vAuLTs Filed March 27. 1967 "HUUDUDDUUUU,

Inventor. Cazence :fa/Yer' 5y 3M vttorpy United States Patent O 3,394,645 COOLING BAFFLE AND TAMPER SHIELD FOR UNDERGROUND TRANSFORMER VAULTS Clarence R. Acker, Zanesville, Ohio, assignor to Mc- Graw-Edison Company, Milwaukee, Wis., a corporation of Delaware Filed Mar. 27, 1967, Ser. No. 626,330 12 Claims. (Cl. 98--32) ABSTRACT OF THE DISCLOSURE A below-ground level vault for a transformer and havin-g a vertical side wall portion, a cover grate aud a baille assembly disposed adjacent the upper end of the vault and including an outer, open-ended, truncated conical member and a second member spaced from and disposed within the first member. The outer member separates and directs heated lair discharging from the vault and cool incoming air, and the lsecond member acts as a tamper shield and coacts with the first member for directing heated air away from the incoming cooling air.

Background j the invention This invention relates to vaults for housing electrical. apparatus, such as transformers, and which are disposed wholly or partially below ground level, and more particularly to a baille assembly for ventilation and safety.

Vaults disposed -below ground level for housing transformers should be vented if the transformer is to be operated at its rated value. Simple grate-type covers are not satisfactory, however, because they expose high voltage portions of the transformer and do not properly separate the cool incoming air from the heated air discharging from the vault.

One type of prior art underground transformer ventilation system includes inlet pipes which open at their upper end into the ambient and at their other end to the lower end of the vault. In addition, discharge openings are disposed above the upper end of the transformer. This type of installation was not found to be wholly satisfactory, because it tends to cause an inordinately high transformer top oil temperature when the transformer is operated under overload or high thermal conditions.

Summary of the invention In general terms, the invention comprises an enclosure having a vented upper end and side walls for enclosing electrical apparatus and a baille assembly disposed between the upper end of the enclosure and the electrical apparatus for intercepting all straight line paths therebetween, wherein the bale assembly is constructed and arranged to intercept heated air from the electrical apparatus and to direct the same toward a central portion of the vented upper end and for intercepting cooling air entering the enclosure through the vented upper end and to direct the same toward the side walls of the enclosure.

Brief description of the drawings parts broken away,

' Description ofthe preferred embodiment FIG. 1 shows a vault 10 disposed below ground level and for enclosing a transformer 11. The vault 10 may include a generally tubular, open-ended housing member 12, which is composed of any suitable material, such as bituminous fiber, and which is disposed in a prepared excavated opening 14. The oor yof the vault 10 may be covered with gravel 15 for supporting the transformer 11 and to promote drainage.

A grate 16, or other suitably vented member, covers the exposed upper end of the vault to provide ventilation and prevent tampering. The'grate 16 is shown in FIG. 2 to have a large plurality of closely spaced openings 17 to permit the free flow of air into the vault 10. v

The transformer 11 may be of any conventional type and may, for example, have a high voltage bushing 18 connected to a primary conductor 19 and low voltage ybushings 20 which are connected to secondary conductors 22. A bafe assembly 24 is mounted adjacent the upper end of the vault 12 and above the transformer 11 for separating and directing the incoming cooling air and the heated discharge air and to prevent tampering with the transformer 11.

The shield assembly 24 is mounted at the upper end of the housing 12 by means of a plurality of elongate strap members 26 whose opposite ends engage the housing 12 and the assembly 24. More specifically, each of the strap members 26 may be bent at one end to form support hooks 27 for engaging the upper edge of the housing 12. In addition, each of the strap members 26 may also include a central portion 29 which extends downwardly and inwardly toward the center `of the housing 12 and terminates at their inner ends in a generally horizontally extending portion 31 for engaging the shield assembly 24.

The shield assembly 24 is shown in FIGS. l, 3 and 4 to include a hollow, inverted, generally bowl-shaped outer shield member 32 and a generally more shallow inner shield member 33 which is disposed within and spaced from the outer member 32. The assembly 24 is generally symmetrical about a vertical axis and is supported by the strap members 26 in a generally concentric relation relative to the longitudinal axis of the housing 12.

The outer shield member 32 includes a generally frustoconical upper portion 35 which has an enlarged central opening 36. In addition, a generally cylindrical skirt portion 38 extends downwardly from the upper portion 35 and in general parallelism with the housing member 12. The opening 36 is disposed directly below and has a diameter substantially smaller than that of the grate 16. The upper portion 35 of shield member 32 slopes downwardly and outwardly toward the housing 12 with the skirt portion 38 having a diameter smaller than that of said housing 12.

The second shield member 33 is spaced from the upper member 32 and disposed directly below the opening 36. The diameter of the second shield mem-ber 33 is between that of the opening 36 and the skirt portion 38.

Each of the shield members 32 and 33 may have a plurality of spaced apart embossments 40 and 41, respectively, which extend toward the other and are in substantial registry for embracing the opposite sides of the strap portion 31. Toward this end member 32 has a small slot 42 formed adjacent each embossment 40 to permit the strap members 26 to pass therethrough.

In addition, the shield members 32 and 33 may be secured to tbe strap members 26 and each other in any suitable manner to provide a unitary assembly. In the illustrated embodiment, for example, this is achieved by a sc-rew 43 whose head 44 engages the inner shield 33 and an internally threaded metallic sleeve member 45 which is threadably engaged by the screw 43 and which has a head portion 46 for engaging the upper shield member 32.

As those skilled in the art will appreciate, the shield members 32 and 33 may be formed of any suitable electrical insulating material, such as, for example, polyvinyl chloride.

Referring again to FIG. l, it can be seen that the heated air rising from the transformer 11 and represented by the arrows 5) will be forced by the inner shield 33 to move outwardly toward the outer shield 32. The heated air 5i) is then intercepted by the outer shield 32 and directed along the conical portion 3S and through the gap between the shields 32 and 33 and toward the central opening 36. In this manner the shields 32 and 33 direct the heated air rising from the transformer 11 toward the central portion of the grate 16. Simultaneously, cool outside air, represented by the arrows 52, is drawn into the vault along the outside portion of the grate 16 and is intercepted by the upper surface of the outer shield 32 and is directed outwardly and downwardly through the gap between the skirt portion 38 and the housing 12.

It can be seen, therefore, that the outer shield separates the heated discharging air S0 and the cooling incoming air 52 and directs the same into a turbulencefree path around the transformer 11. The configuration of the shields 32 and 33 insures that this air ilow will be accomplished with a minimum of turbulence.

In addition, the shield assembly 24 prevents inadvertent or deliberate contact with the transformer 11 or the energized conductors or connectors within the vault 12. This is accomplished without the introduction of air turbulence between the heated discharge air and the cooler incoming air, as in the case of conventional louveredtype baies.

It has been found that the baille configuration of the preferred embodiment of the invention yields a significantly lower transformer top oil temperature than is yielded by the same vault and grate conguration taken alone, as well as various types of louvered covers, bailles and conduits.

While only the preferred embodiment of the invention has been shown and described, and while the invention has been illustrated with respect to a single vault configuration, it is not intended to be limited thereby, but only by the scope of the appended claims.

I claim:

1. ln combination, an enclosure including side walls and a cover at its upper end having a plurality of spaced perforations formed therein, electrical apparatus disposed within said enclosure, a baille assembly disposed between the upper end of said enclosure and said electrical apparatus for intercepting all straight line paths therebetween, said baflle assembly having upper and lower surfaces and being located above said electrical apparatus wherein its lower surface intercepts heated air rising from said electrical apparatus and its upper surface intercepts cooling air entering said enclosure through said cover, said baille being contoured to direct the heated air upwardly and inwardly toward a central portion of said apertured cover and said cooling air downwardly and outwardly toward the side walls of said enclosure, whereby the heated discharged air will not be recirculated through said enclosure.

2. The combination set forth in claim 1 wherein said baille assembly includes an outer shield member for intercepting heated air from said electrical apparatus and directing the same toward a central portion of said vented upper end and for intercepting cooling air entering said enclosure through said vented upper end and directing the same toward the side walls of said enclosure and an inner shield member spaced from said outer member and disposed between said vented upper end and said electrical apparatus.

3. The combination set forth in claim 2 wherein said electrical apparatus is inductive and wherein said vented upper end comprises a cover having a plurality of spaced openings formed therein, said battle assembly -being disposed below the upper end of said enclosure and above said inductive apparatus, said outer shield member having a wall portion sloping generally inwardly and upwardly relative to said enclosure and terminating in an aperture disposed below said cover.

4. The assembly set forth in claim 3 wherein said inner shield member is larger than said aperture and smaller than the adjacent portions of said sloping wall portion.

5. The assembly set for-th in claim 3 wherein said wall portion has a generally frusto-conical configuration wherein its smaller diameter end is disposed adjacent said cover and defines the margin of said aperture.

6. The assembly set forth in claim 3 wherein said outer shield member includes a skirt portion extending downwardly from the lower end of said sloping wall portion.

7. The assembly set forth in claim 3 and including a plurality of suppor-t members having one end engaging the upper end of said enclosure and their other ends engaging said baille assembly.

8. The combination set forth in claim 3 wherein said enclosure has a substantial cylindrical side wall portion, said baille assembly is substantially symmetrical about the vertical axis of said enclosure.

9. The assembly set forth in claim 5 wherein said inner shield member is larger than said aperture and smaller lthan the large diameter end of said wall portion, said inner shield member also having substantially conical conilguration which has a shallower slope than said inclined wall portion.

10. The assembly set forth in claim 9 wherein said outer shield includes a skirt portion extending downwardly from the large diameter end of said wall portion.

11. The combination set forth in claim 10 wherein said enclosure has a substantial cylindrical side wall portion, said baille assembly being substantially symmetrical about the vertical axis of said enclosure.

12. The assembly set forth in claim 11 and including a plurality of support members having one end engaging the upper end of said enclosure and their other ends engaging said baille assembly.

ROBERT A. OLEARY, Primary Examiner. 

